Conventionally a plurality of integrated circuits are formed simultaneously on a semiconductor substrate, and the substrate is then diced to form individual integrated circuits. Apparatus is know for feeding substrates into such a dicing machine, and for sorting the diced integrated circuits.
One type of integrated circuit which is becoming increasingly popular is one having an array of multiple electrical contacts (typically solder balls, known as a ball grid array (BGA) packages, and pads in non-leaded packages, known as a Quad Flatpack Non-Leaded (QFN) packages) in an array on one of its major faces. The dicing of a substrate having a ball grid array on one of its surfaces is typically performed with the surface of the substrate carrying the balls facing upwards. It is known to perform a limited number of sorting operations on the singulated integrated circuit units to detect abnormal (faulty) units. At each stage of the process following singulation of the integrated circuit units, the manipulation of the units requires a firm engagement of the units. In some circumstances this is achieved a vacuum seal whereby the unit is held within a matrix by suction. In one arrangement a metal “manifold” having an internal hollow portion which is applied a vacuum will have a surface divided into an array of recesses with an aperture for each recess through which the vacuum will draw the units.
The units themselves are delicate and can suffer damage through the manipulation process and particularly, when draw near to the respective metal recesses of the surface. For this reason, a layer or coating of a soft material such as rubber is placed on the surface such that the unit contacts the soft layer rather than the metal surface.
Because of the fine tolerances required for holding the small units it is a particularly complex task to bond the layer to the metal surface. One difficulty in this duplication process is the different tolerances required of the metal surface as compared to the soft material. Therefore, the element having the metal surface with the layer and the vacuum manifold are generally expensive items should themselves need to be treated with care.
As a result of the manufacturing process, it is inevitable that the soft material layer will either wear or suffer damage. To prevent damage to the units, it is therefore necessary to replace the soft material layer. However, because of the aforementioned difficulties replacing the soft metal layer will also require replacement of the entire element.
It is therefore an object of the present invention to reduce the cost of replacement imposed by wear or damage.